#!/bin/bash

# Copyright 2015 Martin Preisler <martin@preisler.me>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

function die()
{
    echo "$*" >&2
    exit 1
}

function invalid()
{
    echo -e "$*\n" >&2
    usage
    exit 1
}

function usage()
{
    echo "oscap-vm -- Tool for offline SCAP evaluation of virtual machines."
    echo
    echo "Usage:"
    echo
    echo "$ oscap-vm [--oscap=<oscap_binary>] image VM_STORAGE_IMAGE xccdf eval [options] INPUT_CONTENT"
    echo "$ oscap-vm [--oscap=<oscap_binary>] domain VM_DOMAIN xccdf eval [options] INPUT_CONTENT"
    echo
    echo "supported oscap xccdf eval options are:"
    echo "  --profile"
    echo "  --tailoring-file"
    echo "  --tailoring-id"
    echo "  --cpe (external OVAL dependencies are not supported yet!)"
    echo "  --oval-results"
    echo "  --check-engine-results"
    echo "  --results"
    echo "  --results-arf"
    echo "  --report"
    echo "  --skip-valid"
    echo "  --fetch-remote-resources"
    echo "  --progress"
    echo "  --datastream-id"
    echo "  --xccdf-id"
    echo "  --benchmark-id"
    echo
    echo "$ oscap-vm image VM_STORAGE_IMAGE oval eval [options] INPUT_CONTENT"
    echo "$ oscap-vm domain VM_DOMAIN oval eval [options] INPUT_CONTENT"
    echo
    echo "supported oscap oval eval options are:"
    echo "  --id"
    echo "  --variables"
    echo "  --directives"
    echo "  --results"
    echo "  --report"
    echo "  --skip-valid"
    echo "  --datastream-id"
    echo "  --oval-id"
    echo
    echo "$ oscap-vm image VM_STORAGE_IMAGE oval collect [options] INPUT_CONTENT"
    echo "$ oscap-vm domain VM_DOMAIN oval collect [options] INPUT_CONTENT"
    echo
    echo "supported oscap oval collect options are:"
    echo "  --id"
    echo "  --syschar"
    echo "  --variables"
    echo "  --skip-valid"
    echo
    echo "See \`man oscap\` to learn more about semantics of these options."
}

OSCAP_BINARY=oscap

if [ $# -lt 1 ]; then
    invalid "No arguments provided."
elif [ "$1" == "-h" ] || [ "$1" == "--help" ]; then
    usage
    exit 0
elif [[ "$1" == --oscap=* ]] && [ $# -gt 3 ]; then
    OSCAP_BINARY=${1#"--oscap="}
    shift
elif [ "$1" == "image" ] && [ $# -gt 2 ]; then
    true
elif [ "$1" == "domain" ] && [ $# -gt 2 ]; then
    true
else
    invalid "Invalid arguments provided."
fi

hash guestmount 2> /dev/null || die "Cannot find guestmount, please install libguestfs utilities."

if hash guestunmount 2> /dev/null; then
    UNMOUNT_COMMAND="guestunmount"
elif hash fusermount 2> /dev/null; then
    echo "guestunmount command not present on the system, using simpler fusermount instead"
    UNMOUNT_COMMAND="fusermount -u"
else
    die "Cannot find guestunmount or fusermount, please install libguestfs utilities, or fuse."
fi

hash mktemp 2> /dev/null || die "Cannot find mktemp, please install coreutils."

MOUNTPOINT=$(mktemp -d)

if [ "$1" == "image" ]; then
    echo "Mounting guestfs image '$2' to '$MOUNTPOINT'..."
    guestmount -a "$2" -i --ro "$MOUNTPOINT"
    if [ $? -ne 0 ]; then
        rmdir "$MOUNTPOINT"
        die "Failed to mount image '$2' to '$MOUNTPOINT'!"
    fi
elif [ "$1" == "domain" ]; then
    echo "Mounting guestfs domain '$2' to '$MOUNTPOINT'..."
    guestmount -d "$2" -i --ro "$MOUNTPOINT"
    if [ $? -ne 0 ]; then
        rmdir "$MOUNTPOINT"
        die "Failed to mount guestfs domain '$2' to '$MOUNTPOINT'!"
    fi
fi

# Learn more at https://www.redhat.com/archives/open-scap-list/2013-July/msg00000.html
export OSCAP_PROBE_ROOT
OSCAP_PROBE_ROOT="$(cd "$MOUNTPOINT" && pwd)" || die "Unable to change current directory to OSCAP_PROBE_ROOT (MOUNTPOINT)."
export OSCAP_EVALUATION_TARGET="oscap-vm $1 $2"
shift 2

$OSCAP_BINARY "$@"
EXIT_CODE=$?
echo "Unmounting '$MOUNTPOINT'..."
$UNMOUNT_COMMAND "$MOUNTPOINT"
rmdir "$MOUNTPOINT"
exit $EXIT_CODE
